Virtually all consumer products are sold in packages, such as cardboard cartons, boxes, and other types of containers. A package has two very distinguishing features: a structural design and a graphical design. The structural design of a package is defined by the package's structural features, such as the dimensions, geometric shape, and material of the package. The graphical design of a package is defined by the colors, artwork, and other images applied thereto. The graphical design preferably identifies the packaged product in a manner which is aesthetically appealing to potential consumers.
A package is typically formed from a sheet of corrugated board, carton board, or other work material upon which a graphical design is applied. The graphical design may be applied by many known processes. For example, a sheet having a design may be laminated to the package, or the package itself may be printed.
One common printing method is that of flexography. A flexographic print is made by creating a positive mirrored master of the required image as a 3D relief in a rubber or polymer material. Flexographic plates can be created with analog and digital platemaking processes. The image areas are raised above the non-image areas on the rubber or polymer plate. The ink is transferred from the ink roll which is partially immersed in the ink tank. Then it transfers to the anilox roll (or meter roll) whose texture holds a specific amount of ink since it's covered with thousands of small wells or cells that enable it to meter ink to the printing plate in a uniform thickness evenly and quickly (the number of cells per linear inch can vary according to the type of print job and the quality required). To avoid getting a final product with a smudgy or lumpy look, it must be ensured that the amount of ink on the printing plate is not excessive. This is achieved by using a scraper, called a doctor blade. The doctor blade removes excess ink from the anilox roller before inking the printing plate. The substrate is finally sandwiched between the plate and the impression cylinder to transfer the image.
Components of the composition of a flexographic ink may include but are not limited to: a vehicle such as a solvent or water; a coloring element such as a pigment, pigment grinding, and letdown vehicles in colloidal, solution, or emulsion form; and other components which may include but are not limited to wax, pH control agents, viscosity modifiers, antifoamers, dispersants, antimicrobial agents, ink transfer agents, and drying speed modification agents. The vehicle may contain a combination of acrylic, maleic, fumaric, or other resins.
Water based flexographic inks typically contain acrylic polymers to give the ink good transfer, stability, and resolubility when applied to a substrate, such as corrugated board on constituent linerboard. The acrylic polymers are conventionally produced from petroleum feedstock. Use of such acrylic polymers introduce several concerns, including: 1) the supply and pricing of petroleum is quite volatile and subject to disruption from external events 2) petroleum is a fossil fuel available in finite quantities, i.e., it is a non-renewable resource and its supply cannot be sustained indefinitely 3) the use of fossil fuels increases carbon footprint and subsequent environmental damage.
Alternative polymers to petroleum based acrylic polymers used in inks are available and known in the industry. One prime example of a non-petroleum based ink polymer is soy protein. However, use of soy protein as a biofuel and foodstuff compete with its use in flexographic inks and such other uses are economically preferred. As with petroleum based polymers, this also gives rise to significant fluctuations in supply and pricing.
Therefore, there exists a need for a polymer that is renewable and otherwise environmentally friendly, can be easily sourced and is not sensitive to fluctuations in pricing due to supply and demand from other uses.